Unfortunately the link you found leads to an older version of the documentation. If you click on the menu on the left side of that page, the latest documentation at Realm Sync Documentation | 3.16.0 | Realm Sync (LEGACY) no longer mentions self-hosted installation.
Thanks for sharing how you found the link – I’ve created a docs issue to update older versions of the documentation so the messaging is consistent.
I understand there may be legal requirements to meet where self-hosting is the most straightforward option. There may also be alternatives via dedicated Realm Cloud, but that’s a conversation to have with our sales team.
The current product development focus is as per the public roadmap to MongoDB Realm which will integrate the Realm Cloud with MongoDB Stitch and Atlas. MongoDB Cloud services have enterprise-level security, reliability, and compliance (see: MongoDB Trust Center).
Regards,
Stennie